In counting machines of the type contemplated by the present invention and described in the cross-referenced patent application, a conveyor carries a plurality of elongated slat members having uniformly spaced cavities provided therein, each of which is caused to contain a tablet, capsule, or the like, to be counted. The slats are carried in a closed loop path in a direction transverse to the direction of slat elongation are are gradually inverted in order to discharge their contents into chutes or containers for counting. Because of present day multi-shaped capsules and tablets, many uncoated, it is not an infrequent occurrence for a cavity to fail to discharge its capsule due to an absence of one in that cavity, or a wedging of one therein, either of which fault may produce a miscount, and, if not corrected, may provide continuous miscounts. With more stringent controls being emphasized by federal drug agencies as well as more accurate counts by corporate quality control departments, it becomes increasingly important to detect any missing articles, or wedged articles which suitable ejector means has failed to unwedge, and to indicate such fault or condition to the operator for corrective action.
The present invention satisfies the abovementioned requirements. Briefly, the invention provides a light source beneath each slat cavity of a single row, and photoelectric detecting means in opposing receiving relationship to the light sources for sensing an empty cavity, or a wedged article or product in a cavity. Visible lamp means will indicate a fault, i.e., an empty or wedged cavity and the particular bottle associated therewith which has, or will receive the miscount. The visible means may be accompanied by an audible alarm signal. The operator, in response to such fault indication, can usually correct the fault by performing a simple corrective manual operation, or automatic functions may be triggered into action by means of output signals generated by the photodetecting means, such, for example, as shunting an appropriate bottle off the conveyor line .